Lubricating composition based on aminated compounds

ABSTRACT

A lubricant composition includes at least one base oil and at least one amine compound. The lubricant composition simultaneously has good anti-wear and fuel economy properties as well as good antioxidant properties.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a National Phase Entry of International Application Serial No. PCT/EP2014/053080, filed on Feb. 18, 2014, which claims priority to French Patent Application Serial No. 13 51 410, filed on Feb. 19, 2013, both of which are incorporated by reference herein.

BACKGROUND AND SUMMARY

The present invention relates to the field of lubricants. More particularly, the present invention relates to a lubricant composition comprising at least one amine compound. The lubricant composition according to the invention has, simultaneously, good anti-wear and fuel economy properties as well as good antioxidant properties. The present invention also relates to a method utilizing this composition.

The present invention also relates to a method for reducing the fuel consumption of a vehicle utilizing this lubricant composition. The present invention also relates to a method for reducing the oxidation of a lubricant composition by the addition of an amine compound to this composition. The present invention also relates to the use of an amine compound as a friction modifier in a lubricant composition. The present invention also relates to the use of an amine compound as an antioxidant in a lubricant composition.

Lubricant compositions, and more particularly engine lubricant compositions, are known as being able to comprise different types of additives, making it possible to provide the composition with particular properties. Among these additives, antioxidants are commonly used. In fact, in the presence of air and heat, a lubricant composition can react to form acids or other oxygen-containing compounds. The antioxidant is then added to the lubricant composition in order to reduce or even prevent the formation or propagation of the intermediate compounds, such as the radicals or the peroxides, making it possible to reduce or even stop the oxidation of the composition. The antioxidants commonly used in the field of lubricants are chosen from zinc dithiophosphates, phenolic compounds, aromatic amines, these compounds being able to be used alone or in a mixture.

However, they can have certain drawbacks. In fact, the major drawback of zinc thiophosphates is that they are carriers of metals and comprise sulphur, which is not desirable in lubricants with a low sulphated ash content, a low phosphorus content and a low sulphur content, commonly called “low sap” lubricants. Moreover, the use of phenolic compounds could be limited in lubricant compositions, due to the potential risks of these compounds to human health, in particular through their toxicity, persistence and bioaccumulation by the organism.

As for the aromatic amines, their antioxidant effectiveness is recognized for low-temperature use of a lubricant composition, thus reducing their usefulness under high-temperature conditions corresponding to the operating conditions of an engine. Moreover, following the establishment of the Kyoto protocol, new standards protecting the environment require the automobile industry to construct vehicles having reduced pollutant emissions and fuel consumption. As a result, the engines of these vehicles are subject to increasingly stringent technical constraints: in particular they run more quickly, at increasingly high temperatures, and are required to consume less and less fuel.

The nature of engine lubricants for automobiles has an influence on the emission of pollutants and on fuel consumption. Engine lubricants for automobile engines, called energy-saving or “fuel-eco”, have been developed in order to meet these new requirements. The improvement in the energy performance of lubricant compositions can be obtained in particular by mixing specific additives such as friction modifiers into base oils.

Among the friction modifiers, the organometallic compounds comprising molybdenum, such as molybdenum dithiocarbamates, are commonly used. In order to obtain good anti-friction properties, a sufficient quantity of molybdenum must be present within the lubricant composition. However, these compounds have the drawback of causing the formation of sediments when the lubricant composition has too high a content of elemental molybdenum. The poor solubility of some of these compounds modifies, or even degrades the properties of the lubricant composition, in particular its viscosity. Now, a composition which is too viscous or not viscous enough militates against the movement of the mobile parts, easy starting of an engine, the protection of an engine when it has reached its operating temperature, and therefore ultimately causes in particular an increase in fuel consumption. Furthermore, these molybdenum dithiocarbamates contribute to increasing the ash content, reducing their potential for use in a lubricant composition, in particular in Europe.

Different technical solutions for replacing the compounds based on molybdenum have been described. Document U.S. Pat. No. 4,505,835 describes a lubricant composition comprising an amine compound as friction modifier. However, this amine compound is defined by a specific chemical structure comprising an ammonium function. Now, compounds comprising an ammonium function, when added to a lubricant composition, present a potential risk of thickening the composition, thus being able to alter the lubrication properties of the composition. Moreover, no indication is given in this document as to the existence of antioxidant properties of this compound. Furthermore, this document teaches more particularly the application of the lubricant composition in the field of marine lubricants.

Moreover, the combination of antioxidants and friction modifiers in a lubricant composition does not necessarily guarantee that satisfactory antioxidant and anti-wear properties will be obtained, due to the fact that these compounds can potentially neutralize each other. As formulation and fuel economy requirements are increasing, there is therefore still a need to seek novel polyfunctional compounds having both antioxidant and friction-modifying properties which, once formulated in a lubricant composition, do not destabilize it, and simultaneously allow improved oxidation-resistance and fuel economy properties to be obtained.

An objective of the present invention is to provide a compound, as well as a lubricant composition comprising said compound, that overcomes all or part of the aforementioned drawbacks. Another objective of the invention is to provide a lubricant composition the formulation of which is easy to implement. Another objective of the invention is to provide a lubricant composition having antioxidant properties during low-temperature and high-temperature use. Another objective of the present invention is to provide a lubrication method allowing energy savings.

The subject of the invention is thus a lubricant composition comprising at least one base oil and at least one amine compound of formula (I)

in which:

-   -   M represents a hydronium, sodium, potassium, lithium or ammonium         cation;     -   R₁ represents a hydrogen atom or a linear or branched alkyl         group, comprising from 1 to 30 carbon atoms;     -   R₂ represents a linear or branched alkyl group, comprising from         2 to 20 carbon atoms;     -   R₃ represents a linear or branched alkyl group, comprising from         2 to 20 carbon atoms;     -   n represents 2, 3, 4, 5 or 6.

It is known from document EP1462093A2 to add a compound of formula (I) to an aqueous medium comprising at least one oxidation base and/or at least one direct dye and at least one polycarboxylic acid or one of these salts. The compositions obtained are essentially dye compositions and are used for colouring hair. However, this document does not mention the use of a compound of formula (I) in a base oil for the formulation of lubricant composition.

Document U.S. Pat. No. 3,687,852 describes the use of aspartic acid derivatives (compounds different from the compounds of formula (I)) in a lubricant composition in order to improve the lubrication properties thereof.

Surprisingly, the applicant found that the presence of an amine compound of formula (I) in a lubricant composition makes it possible to confer good antioxidant properties on the composition, as well as good anti-friction properties, and thus good fuel economy properties. Thus, the present invention makes it possible to formulate lubricant compositions comprising no, or very little, antioxidants chosen from zinc dithiophosphates, phenolic compounds, aromatic amines, and nevertheless having equivalent, or even improved, antioxidant properties. The present invention also makes it possible to formuate lubricant compositions comprising no, or very little, friction modifiers based on molybdenum and nevertheless having equivalent, or even improved, anti-friction and fuel economy properties. Advantageously, the lubricant compositions according to the invention have an improved stability on storage, as well as a viscosity that varies very little or not at all over time.

In an embodiment, the lubricant composition consists essentially of at least one base oil and at least one amine compound of formula (I)

in which:

-   -   M represents a hydronium, sodium, potassium, lithium or ammonium         cation;     -   H₁ represents a hydrogen atom or a linear or branched alkyl         group, comprising from 1 to 30 carbon atoms;     -   R₂ represents a linear or branched alkyl group, comprising from         2 to 20 carbon atoms;     -   R₃ represents a linear or branched alkyl group, comprising from         2 to 20 carbon atoms;     -   n represents 2, 3, 4, 5 or 6.

The invention also relates to an engine oil comprising a lubricant composition as defined above. The invention also relates to a transmission oil comprising a lubricant composition as defined above. The invention also relates to an industrial lubricating oil comprising a lubricant composition as defined above. By industrial lubricating oil according to the invention, is meant any lubricating oil for use in the lubrication of devices, in particular mechanical, hydraulic or other devices, used in industry, such as greases, oils intended for metal working, compressor oils, turbine oils, chain oils, linkage oils, insulating oils such as electric transformer oils, oils suitable for heat transfer, oils for refrigerant devices or also hydraulic fluids.

Thus, the invention also relates to a hydraulic fluid comprising a lubricant composition as defined above. The invention also relates to the use of a lubricant composition as defined above for the lubrication of a light-vehicle or lorry engine. In an embodiment, the invention relates to the use of a lubricant composition as defined above for the lubrication of a light-vehicle gasoline or diesel engine.

The invention also relates to the use of a lubricant composition as defined above for reducing the fuel consumption of vehicles. The invention also relates to a method for lubricating a light-vehicle or lorry engine comprising at least one step of bringing the engine into contact with a lubricant composition as defined above.

In an embodiment, the invention relates to a method for lubricating a light-vehicle gasoline or diesel engine comprising at least one step of bringing the engine into contact with a lubricant composition as defined above.

The invention also relates to a method for reducing the energy losses by friction of a mechanical part comprising at least one step of bringing a mechanical part into contact with a lubricant composition as defined above. The invention also relates to a method for reducing the fuel consumption of a vehicle comprising at least one step of bringing a mechanical part of the vehicle engine into contact with a lubricant composition as defined above.

The invention also relates to the use of an amine compound of formula (I) as an antioxidant in a lubricant composition

in which:

-   -   M represents a hydronium, sodium, potassium, lithium or ammonium         cation;     -   R₁ represents a hydrogen atom or a linear or branched alkyl         group, comprising from 1 to 30 carbon atoms;     -   R₂ represents a linear or branched alkyl group, comprising from         2 to 20 carbon atoms;     -   R₃ represents a linear or branched alkyl group, comprising from         2 to 20 carbon atoms;     -   n represents 2, 3, 4, 5 or 6.

The invention also relates to the use of an amine compound of formula (I) as friction modifier in a lubricant composition

in which:

-   -   M represents a hydronium, sodium, potassium, lithium or ammonium         cation;     -   R₁ represents a hydrogen atom or a linear or branched alkyl         group, comprising from 1 to 30 carbon atoms;     -   R₂ represents a linear or branched alkyl group, comprising from         2 to 20 carbon atoms;     -   R₃ represents a linear or branched alkyl group, comprising from         2 to 20 carbon atoms;     -   n represents 2, 3, 4, 5 or 6.

The invention also relates to a method for reducing the oxidation of a lubricant composition comprising the addition of a compound of formula (I) to said lubricant composition

in which:

-   -   M represents a hydronium, sodium, potassium, lithium or ammonium         cation;     -   R₁ represents a hydrogen atom or a linear or branched alkyl         group comprising from 1 to 30 carbon atoms;     -   R₂ represents a linear or branched alkyl group, comprising from         2 to 20 carbon atoms;     -   R₃ represents a linear or branched alkyl group, comprising from         2 to 20 carbon atoms;     -   n represents 2, 3, 4, 5 or 6.

DETAILED DESCRIPTION

Amine Compound

The amine compound present in the lubricant composition according to the invention is a compound of formula (I)

in which:

-   -   M represents a hydronium, sodium, potassium, lithium or ammonium         cation;     -   R₁ represents a hydrogen atom or a linear or branched alkyl         group, comprising from 1 to 30 carbon atoms;     -   R₂ represents a linear or branched alkyl group, comprising from         2 to 20 carbon atoms;     -   R₃ represents a linear or branched alkyl group, comprising from         2 to 20 carbon atoms;     -   n represents 2, 3, 4, 5 or 6.

In a preferred embodiment, M represents a sodium cation. In an embodiment, R₁ can represent a linear or branched alkyl group, comprising from 5 to 20 carbon atoms, preferably from 9 to 15 carbon atoms. In a preferred embodiment, R₁ represents a linear alkyl group comprising from 1 to 30 carbon atoms, preferably from 5 to 20 carbon atoms, advantageously from 9 to 15 carbon atoms. In a preferred embodiment, R₂ represents a linear or branched alkyl group, comprising from 2 to 5 carbon atoms. In a preferred embodiment, R₃ represents a linear or branched alkyl group, comprising from 2 to 5 carbon atoms. In an embodiment, n represents 2, 3 or 4.

In a preferred embodiment of the invention, the amine compound can be chosen from the compounds of formula (I) in which:

-   -   M represents a sodium cation,     -   R₁ represents a linear group alkyl, comprising from 5 to 20         carbon atoms, preferably from 9 to 15 carbon atoms,     -   R₂ represents a linear or branched alkyl group, comprising from         2 to 5 carbon atoms,     -   R₃ represents a linear or branched alkyl group, comprising from         2 to 5 carbon atoms, and     -   n represents 2, 3 or 4.

In an embodiment of the invention, R₁ represents a hydrocarbon-containing group which is obtained after reduction of lauric acid. Preferably, the lauric acid is obtained by extraction from coconut oil.

Advantageously, the amine compound is a compound of formula (Ia)

As an example of amine compounds according to the invention, the product Chimexane HB marketed by the Chimex company can be mentioned. In an embodiment, the content by weight of amine compound of formula (I) ranges from 0.01 to 3%, preferably from 0.5 to 2% with respect to the total weight of the composition.

In an embodiment, the invention relates to a lubricant composition comprising:

-   -   at least one compound of formula (I),     -   an antioxidant of the zinc dithiophosphate type at a content         less than or equal to 0.5%, preferably ranging from 0.01 to 0.5%         by weight with respect to the weight of the lubricant         composition.

In an embodiment, the invention relates to a lubricant composition comprising:

-   -   at least one compound of formula (I),     -   an antioxidant of the phenolic compound type at a content less         than or equal to 2%, preferably ranging from 0.01 to 2% by         weight with respect to the weight of the lubricant composition.

In an embodiment, the invention relates to a lubricant composition comprising:

-   -   at least one compound of formula (I),     -   an antioxidant of the aromatic amine type at a content less than         or equal to 2%, preferably ranging from 0.01 to 2% by weight         with respect to the weight of the lubricant composition.

In an embodiment, the invention relates to a lubricant composition comprising:

-   -   at least one compound of formula (I),     -   a friction modifier based on molybdenum at a content less than         or equal to 0.25%, preferably ranging from 0.01 to 0.25% by         weight with respect to the weight of the lubricant composition.

Another subject of the invention relates to the use of an amine compound of formula (I) as an antioxidant in a lubricant composition

in which:

-   -   M represents a hydronium, sodium, potassium, lithium or ammonium         cation;     -   R₁ represents a hydrogen atom or a linear or branched alkyl         group, comprising from 1 to 30 carbon atoms;     -   R₂ represents a linear or branched alkyl group, comprising from         2 to 20 carbon atoms;     -   R₃ represents a linear or branched alkyl group, comprising from         2 to 20 carbon atoms;     -   n represents 2, 3, 4, 5 or 6.         All the characteristics and preferences presented for the amine         compound of formula (I) present in the lubricant composition         also apply to the use of an amine compound of formula (I) as an         antioxidant in a lubricant composition.

In a preferred embodiment, the invention relates to the use of an amine compound of formula (Ia) as an antioxidant in a lubricant composition

Another subject of the invention relates to the use of an amine compound of formula (I) as friction modifier in a lubricant composition

in which:

-   -   M represents a hydronium, sodium, potassium, lithium or ammonium         cation;     -   R₁ represents a hydrogen atom or a linear or branched alkyl         group, comprising from 1 to 30 carbon atoms;     -   R₂ represents a linear or branched alkyl group, comprising from         2 to 20 carbon atoms;     -   R₃ represents a linear or branched alkyl group, comprising from         2 to 20 carbon atoms;     -   n represents 2, 3, 4, 5 or 6.         All the characteristics and preferences presented for the amine         compound of formula (I) present in the lubricant composition         also apply to the use of an amine compound of formula (I) as a         friction modifier in a lubricant composition.

In a preferred embodiment, the invention relates to the use of an amine compound of formula (Ia) as a friction modifier in a lubricant composition

Other Compounds of the Lubricant Composition:

Base Oils

The lubricant composition according to the present invention comprises at least one base oil which can be chosen from the base oils of Groups I to V as defined in the API (American Petroleum Institute) classification or its European equivalent: the ATIEL (Association Technique de (I'Industrie Européenne des Lubrifiants) classification or mixtures thereof. The base oil or the mixture of base oils can be of natural or synthetic origin. The base oil or the mixture of base oils can represent at least 50%, preferably at least 60%, more preferentially at least 70%, yet more preferentially at least 80%, with respect to the total mass of the lubricant composition.

The table below sets out the groups of base oils according to the API classification (Publication API No. 1509 Engine Oil Licensing and Certification System appendix E, 14th Edition, December 1996). The percentages are given by weight with respect to the total weight of the base oil composition.

Saturated Viscosity hydrocarbon Sulphur index content content (VI) Group I Mineral oils  <90% >0.03% 80 ≦ VI < 120 Group II Hydrocracked ≧90% ≦0.03% 80 ≦ VI < 120 oils Group III Hydrocracked ≧90% ≦0.03% ≧120 or hydroisomerized oils Group IV (PAO) Polyalphaolefins Group V Esters and other bases not included in bases of Groups I to IV

The oils of Groups I to V can be oils of vegetable, animal, or mineral origin. The base oils referred to as mineral include any type of bases obtained by atmospheric and vacuum distillation of crude oil, followed by refining operations such as solvent extraction, deasphalting, solvent dewaxing, hydrotreating, hydrocracking and hydroisomerization, hydrofinishing. The base oil of the composition according to the invention can also be a synthetic oil, such as certain esters of carboxylic acids and alcohols, or polyalphaolefins. The polyalphaolefins used as base oil, which are distinguished from the heavy polyalphaolefins that can also be present in the compositions according to the invention, can for example be obtained from monomers having from 4 to 32 carbon atoms (for example octene, decene), and have a viscosity at 100° C. ranging from 1.5 to 15 cSt (measured according to the international standard ASTM D445). Mixtures of synthetic and mineral oils can also be used.

Advantageously, the lubricant composition according to the invention is formulated to obtain a kinematic viscosity at 100° C. (KV100) ranging from 4 to 25 cSt, preferably from 5 to 22 cSt, more preferentially from 5 to 13 cSt measured according to the international standard ASTM D445. Advantageously, the lubricant composition according to the invention is formulated to have a viscosity index greater than or equal to 140, preferentially greater than or equal to 150, more preferentially greater than or equal to 160. Advantageously, the lubricant composition according to the invention is presented in the form of an anhydrous composition.

Starting from the examples set out below and on the basis of his general knowledge, a person skilled in the art is able to formulate such compositions. A subject of the invention is also an oil comprising a lubricant composition according to the invention. In an embodiment, a subject of the invention is an engine oil comprising a lubricant composition according to the invention. In an embodiment, a subject of the invention is also a transmission oil comprising a lubricant composition according to the invention. Advantageously, the invention relates to an engine oil comprising a lubricant composition according to the invention.

In an embodiment, the oil according to the invention can be of 0W-20 and 5W-30 grade according to the SAEJ300 classification, characterized by a kinematic viscosity at 100° C. (KV100) ranging from 5.6 to 12.5 cSt measured according to the international standard ASTM D445. In another embodiment, the oil according to the invention can be characterized by a viscosity index, calculated according to the international standard ASTM D2230, greater than or equal to 130, preferably greater than or equal to 150, more preferentially greater than or equal to 160. In order to formulate an engine oil, base oils having a sulphur content of less than 0.3% by weight with respect to the weight of the base oil composition, for example mineral oils of Group III, and sulphur-free synthetic bases, preferentially of Group IV, or mixtures thereof can advantageously be used. Starting from the examples and on the basis of his general knowledge, a person skilled in the art is able to formulate such compositions.

Other Additives

According to an embodiment, the lubricant composition according to the invention can moreover comprise at least one additional additive. The additional additive can be chosen from the group formed by anti-wear additives, extreme-pressure additives, antioxidants different from the amine compound of formula (I), friction modifiers different from the amine compound of formula (I), overbased or non-overbased detergents, polymers improving the viscosity index, pour point improvers, dispersants, anti-foaming agents, thickeners and mixtures thereof. The additive(s) can be introduced alone and/or included in additive packages. The addition of the chosen additive(s) depends on the use of the lubricant composition. These additives and their use depending on the purpose of the lubricant composition are well known to a person skilled in the art. In an embodiment of the invention, the additive(s) are suitable for use as engine oil.

In an embodiment, the lubricant composition can comprise moreover at least one anti-wear additive, at least one extreme-pressure additive or a mixture thereof. The anti-wear and extreme-pressure additives protect the friction surfaces by the formation of a protective film adsorbed on these surfaces. A great variety of anti-wear additives exist, but the category most used in lubricant compositions, in particular for engine oil, is that of the phosphorus- and sulphur-containing additives such as the metallic alkylthiophosphates, in particular the zinc alkylthiophosphates, and more specifically the zinc dialkyldithiophosphates or ZnDTP. The preferred compounds are of formula Zn((SP(S)(OR₄)(OR₅))₂, wherein R₄ and R₅, identical or different, independently represent an alkyl group, preferentially containing from 1 to 18 carbon atoms. The amine phosphates are also anti-wear additives which can be used in the lubricant compositions according to the invention. However, the phosphorus provided by these additives acts as a poison on the catalytic systems of automobiles as these additives generate ashes. These effects can be minimized by partially substituting the amine phosphates with additives which do not provide phosphorus, such as, for example, the polysulphides, in particular the sulphur-containing olefins.

In an embodiment, in particular for an engine application, the anti-wear and extreme-pressure additives can be present in the oil at levels ranging from 0.01 to 6% by mass, preferentially from 0.05 to 4%, preferentially from 0.1% to 2% with respect to the total mass of the engine oil.

In an embodiment of the invention, the lubricant composition can comprise, moreover, at least one additional friction modifier different from the amine compound of formula (I). The additional friction modifier additive can be a compound providing metal elements or an ash-free compound. Among the compounds providing metal elements, there can be mentioned the transition metal complexes such as Mo, Sb, Sn, Fe, Cu, Zn, the ligands of which can be hydrocarbon-containing compounds containing oxygen, nitrogen, sulphur or phosphorus atoms. The ash-free friction modifiers are of organic origin and can be chosen from the monoesters of fatty acids and polyols, alkoxylated amines, alkoxylated fatty amines, fatty epoxides, borated fatty epoxides; fatty amines or glycerol esters of fatty acids. By “fatty” is meant within the meaning of the present invention a hydrocarbon-containing group comprising from 10 to 24 carbon atoms.

In an embodiment, the additional friction modifier additive can be present at levels ranging from 0.01 to 2% by mass, preferentially from 0.1 to 1.5% in the lubricant composition, with respect to the total mass of the lubricant composition. In an embodiment for an engine application, the additional friction modifier additive can be present in the engine oil at levels ranging from 0.01 to 5% by mass, preferentially from 0.1 to 2% in engine oils, with respect to the total mass of the engine oil.

In an embodiment, the lubricant composition can comprise, moreover, at least one additional antioxidant additive different from the amine compound of formula (I). The antioxidant additives slow down the degradation of the lubricant compositions in service, in particular engine oils in service, degradation which can in particular result in the formation of deposits, the presence of sludges, or an increase in the viscosity of the lubricant composition, in particular of the engine oil. The antioxidant additives act in particular as radical inhibitors or hydroperoxide destroyers. Among the additional antioxidants, antioxidants of the phenolic or amine type and phosphorus- and sulphur-containing antioxidants can be mentioned. Some of these antioxidants, for example the phosphorus- and sulphur-containing additives, may generate ashes. The phenolic antioxidants may be ash-free, or be in the form of neutral or basic metal salts.

The additional antioxidant agents can in particular be chosen from the sterically hindered phenols, sterically hindered phenol esters and the sterically hindered phenols comprising a thioether bridge, the diphenylamines, the diphenylamines substituted by at least one C1-C12 alkyl group, the N,N′ dialkyl aryl diamines and combinations thereof. By sterically hindered phenol is meant within the meaning of the present invention a compound comprising a phenol group of which at least one vicinal carbon of the carbon bearing the alcohol function is substituted by at least one C1-C10 alkyl group, preferably a C1-C6 alkyl group, preferably, a C4 alkyl group, preferably by the tert-butyl group. The amine compounds are another class of additional antioxidants which can be used, optionally in combination with the phenolic antioxidants. Typical examples are the aromatic amines of formula R₆R₇R₈N, in which R₆ represents an aliphatic group or an optionally substituted aromatic group, R₇ represents an optionally substituted aromatic group, R₈ represents an optionally substituted aromatic group, R₈ represents a hydrogen atom, an alkyl group, an aryl group or a group of formula R₉S(O)_(z)R₁₀, wherein R₉ represents an alkylene group or an alkenylene group, R₁₀ represents an alkyl group, an alkenyl group or an aryl group and z represents an integer equal to 0, 1 or 2. Sulphur-containing alkyl phenols or their alkali and alkaline-earth metal salts can also be used as additional antioxidants. Another class of additional antioxidants is that of the copper-containing compounds, for example the copper thio- or dithiophosphates, salts of copper and of carboxylic acids, dithiocarbamates, sulphonates, phenates, copper acetylacetonates. Copper I and II, succinic acid or anhydride salts can also be used.

The lubricant composition according to the invention can contain all types of additional antioxidant additives known to a person skilled in the art. Advantageously, ash-free antioxidants are used. In an embodiment, the lubricant composition according to the invention can comprise from 0.5 to 2% of at least one additional antioxidant additive by weight with respect to the total mass of the lubricant composition.

In an embodiment, the lubricant composition according to the invention can also comprise a detergent additive. Detergent additives reduce in particular the formation of deposits on the surface of the metal parts by dissolving the by-products of oxidation and combustion. The detergents that can be used in the lubricant composition according to the invention are well known to a person skilled in the art. The detergents commonly used in the formulation of lubricant compositions can be anionic compounds comprising a long lipophilic hydrocarbon-containing chain and a hydrophilic head. The associated cation is typically a metal cation of an alkali or alkaline-earth metal. The detergents are preferentially chosen from the alkali or alkaline-earth metal salts of carboxylic acids, sulphonates, salicylates, naphthenates, as well as the salts of phenates. The alkali or alkaline-earth metals are preferentially calcium, magnesium, sodium or barium. These metal salts can contain the metal in an approximately stoichiometric quantity or in excess (in a quantity greater than the stoichiometric quantity). In the latter case, these detergents are referred to as overbased detergents. The excess metal providing the detergent with its overbased character is present in the form of metal salts which are insoluble in oil, for example carbonate, hydroxide, oxalate, acetate, glutamate, preferentially carbonate. In an embodiment, the lubricant composition according to the invention can comprise from 2 to 4% by weight of detergent, with respect to the total mass of the lubricant composition.

In an embodiment, the lubricant composition can comprise moreover at least one polymer improving the viscosity index. Polymers improving the viscosity index make it possible in particular to guarantee a good low temperature performance and a minimal viscosity at high temperature, in order to formulate multigrade engine oils in particular. Among these compounds the polymer esters, the olefin copolymers (OCP), the homopolymers or copolymers of styrene, butadiene or isoprene, hydrogenated or not hydrogenated, and the polymethacrylates (PMA) can be mentioned.

In an embodiment, the lubricant composition according to the invention can comprise from 1 to 15% by mass of polymers improving the viscosity index, with respect to the total mass of the lubricant composition. In an embodiment for an engine application, the engine oil according to the invention comprises from 0.1 to 10% by mass of polymers improving the viscosity index, with respect to the total mass of the engine oil, preferably from 0.5 to 5%, preferentially from 1 to 2%.

In an embodiment, the lubricant composition according to the invention can comprise moreover at least one pour point depressant additive. Pour point depressant additives in particular improve the low-temperature behaviour of the lubricant compositions, by slowing down the formation of paraffin crystals. As examples of pour point depressant additives, the alkyl polymethacrylates, polyacrylates, polyarylamides, polyalkylphenols, polyalkylnaphthalenes, alkylated polystyrenes can be mentioned.

In an embodiment, the lubricant composition according to the invention can also comprise at least one dispersant additive, preferably anhydrous. The dispersant additives can be chosen from the groups formed by the succinimides or Mannich bases. In an embodiment, the lubricant composition according to the invention can comprise from 0.2 to 10% in total mass of dispersants, with respect to the total mass of the lubricant composition.

A subject of the invention is also a lubricant composition comprising:

-   -   from 50 to 99.9% by weight of at least one base oil with respect         to the weight of the lubricant composition,     -   from 0.01 to 3% by weight of at least one amine compound of         formula (I) with respect to the weight of the lubricant         composition.         All the characteristics and preferences presented above for the         base oil and the amine compound of formula (I) also apply to the         aforementioned lubricant composition.

A subject of the invention is also a lubricant composition consisting essentially of:

-   -   50 to 99.9% by weight of at least one base oil with respect to         the weight of the lubricant composition,     -   0.01 to 3% by weight of at least one amine compound of         formula (I) with respect to the total weight of the lubricant         composition.         All the characteristics and preferences presented above for the         base oil and the amine compound of formula (I) also apply to the         aforementioned lubricant composition.

A subject of the invention is also a composition, of the concentrated additives type, comprising:

-   -   from 5 to 20%, preferably from 10 to 20% by weight of at least         one amine compound of formula (I) with respect to the weight of         the composition,     -   from 80 to 95% by weight of at least one other additive with         respect to the total weight of the composition.         All the characteristics and preferences presented for the amine         compound of formula (I) and for the additional additive also         apply to the aforementioned lubricant composition.

In an embodiment, the invention relates to a composition comprising:

-   -   from 5 to 20%, preferably from 10 to 20% by weight of at least         one amine compound of formula (I) with respect to the weight of         the composition,     -   from 80 to 95% by weight of at least one other additive chosen         from anti-wear additives, extreme-pressure additives, friction         modifiers different from the amine compound of formula (I),         polymers improving the viscosity index, pour point improvers,         anhydrous dispersants, anti-foaming agents, thickeners and         mixtures thereof, with respect to the weight of the composition.

Advantageously, the composition according to the invention as defined above is presented in the form of a concentrated composition of amine compound of formula (I). In an embodiment of the invention, at least one oil base can be added to the concentrated composition according to the invention in order to obtain a lubricant composition according to the invention.

The Parts

The lubricant composition according to the invention can lubricate at least one mechanical part or one mechanical unit, in particular bearings, gears, universal joints, transmissions, the pistons/rings/liners system, camshafts, clutch, manual or automatic gearboxes, rocker arms, crankcases etc. A subject of the invention is also a method for reducing the energy losses by friction of a mechanical part, said method comprising at least one step of bringing a mechanical part into contact with a lubricant composition according to the invention. All the characteristics and preferences presented for the lubricant composition also apply to the method for reducing the energy losses by friction of a mechanical part according to the invention.

A subject of the invention is also a method for reducing the fuel consumption of a vehicle, the method comprising at least one step of bringing a lubricant composition according to the invention into contact with at least one mechanical part of the engine of the vehicle. In an embodiment, the invention relates to a method for reducing the fuel consumption of a vehicle, in particular of a vehicle being driven only in an urban environment or of a vehicle with an automatic “Stop and Start” system. All the characteristics and preferences presented for the lubricant composition also apply to the method for reducing the fuel consumption of a vehicle according to the invention.

A subject of the invention is also the use of a lubricant composition according to the invention for reducing the fuel consumption of vehicles. In an embodiment, the invention relates to the use of a lubricant composition for reducing the fuel consumption of vehicles at low temperatures, in particular of vehicles being driven only in an urban environment or of vehicles with an automatic “Stop and Start” system. All the characteristics and preferences presented for the lubricant composition also apply to the use for reducing the fuel consumption of vehicles according to the invention.

The vehicles can comprise a two- or four-stroke internal combustion engine. The engines can be gasoline engines or diesel engines intended to be supplied with standard gasoline or diesel. By “standard gasoline” or by “standard diesel” is meant within the meaning of the present invention engines which are supplied with a fuel obtained after refining an oil of mineral origin (such as petroleum for example). The engines can also be gasoline engines or diesel engines modified to be supplied with a fuel based on oils originating from renewable materials such as fuels based on alcohol or biodiesel fuel. The vehicles can be light vehicles such as automobiles and motor cycles. The vehicles can also be lorries, construction machinery, vessels.

A subject of the invention is also the use of a lubricant composition according to the invention for reducing the energy losses by friction of a metal part, preferentially in the bearings, gears or universal joints. All the characteristics and preferences presented for the lubricant composition also apply to the use for reducing the energy losses by friction of a metal part according to the invention.

A subject of the invention is also a method for reducing the oxidation of a lubricant composition comprising the addition of a compound of formula (I) to said lubricant composition. All the characteristics and preferences presented for the amine compound of formula (I) apply to the method for reducing the oxidation of a lubricant composition according to the invention.

The different subjects of the present invention and their implementations will be better understood on reading the examples which follow. These examples are given by way of indication, without being limitative.

EXAMPLE 1 Evaluation of the Antioxidant Properties of Lubricant Compositions According to the Invention

The antioxidant properties of lubricant compositions according to the invention were evaluated, subjected to a high temperature and in the presence of a metal salt as catalyst, based on the method below: A control lubricant composition was prepared according to Table I; the percentages indicated are percentages by mass.

TABLE I Control composition A Group III base oils 65.6% Polyalphaolefin (Spectrasyn 1000 261   3% marketed by the Exxon company) Polyalphaolefin with a kinematic 15.2% viscosity equal to 6 cSt at 100° C. and average molecular mass equal to 470 Daltons Ethylene/propylene copolymer  2.2% (LZ7077 marketed by the Lubrizol company) Branched paraffins  0.2% (LZ7716 marketed by the Lubrizol company) Additive package: dispersants (62.1% 13.8% active material (AM)), calcium sulphonate (4.1% AM), calcium phenates (3.5% AM), aromatic amine antioxidant (5.2% AM), phenolic antioxidant (13.7% AM), zinc dithiophosphate (3.7% AM), anti- foaming agent (0.07% AM)

A composition B (comparative) comprising an antioxidant of the aromatic amine type and a composition C (according to the invention) were prepared according to Table II; the percentages indicated are percentages by mass.

TABLE II A B C (Control) (comparative) (invention) Control composition A 100% 99% 99% Octylated/butylated  1% diphenylamine (100% AM) (Irganox L57 marketed by the CIBA company) Diethylaminopropyl lauryl  1% aminosuccinamate dispersed 55% in water (Chimexane HB marketed by the CHIMEX company)

The antioxidant properties were evaluated according to the following method: Each composition, in a quantity of 27 g, was maintained at a temperature of 170° C. in the presence of a metallic catalyst of formula C₁₅H₂₅FeO₆ diluted in chloroform, and under a flow of air having a flow rate of 10 litres per hour. The duration of the test was 96 hours.

Different quantities of metallic catalyst were used, corresponding to:

-   -   a quantity of iron of 40 ppm,     -   a quantity of iron of 60 ppm,     -   a quantity of iron of 80 ppm.

The oxidation of each composition was evaluated by measuring the increase in kinematic viscosity KV at 40° C. according to the standardized method ASTM D445. The results are presented in Table III and represent the RKV, i.e. the ratio of (kinematic viscosity before testing at 40° C./kinematic viscosity after testing at 40° C.)×100.

TABLE III RKV (40° C.) 40 ppm of iron 60 ppm of iron 80 ppm of iron A 32 258 1349 B 21 129 264 C 18 76 356

The results show that the presence of an amine compound according to the invention in a lubricant composition makes it possible to very significantly improve the antioxidant properties of the composition. It should be noted that the antioxidant properties of a lubricant composition according to the invention are equivalent to, or even better than those of a lubricant composition comprising a usual antioxidant of the aromatic amine type, especially with a content of amine compound according to the invention lower than the content of antioxidant of the aromatic amine type. It should be noted that the lubricant compositions according to the invention retain good antioxidant properties under more stringent oxidation conditions (i.e. corresponding to an iron content of 80 ppm).

EXAMPLE 2 Evaluation of the Coefficient of Friction of Lubricant Compositions According to the Invention

A lubricant composition D (comparative) was prepared according to Table IV; the percentages indicated are percentages by mass.

TABLE IV D (Comparative) Control composition A 99.5% Friction modifier = glycerol 0.5% linoleate (100% AM)

The coefficient of friction of each composition was evaluated by a Cameron Plint laboratory friction test using a reciprocating tribometer of the Cameron-Plint TE-77 type. The test bench is constituted by a cylinder-on-flat tribometer immersed in the lubricant composition to be tested. The coefficient of friction is monitored throughout the test by measuring the tangential force over the normal force. A cylinder (SKF 100C6) having a length of 10 mm and diameter 7 mm is applied onto the steel flat immersed in the lubricant composition to be tested; the temperature of the lubricant composition is set at each test. A sinusoidal reciprocating movement is applied with a defined frequency. Each test lasts for 100 seconds.

Several load levels were studied; 52N, 113N, 115N, 255N, 257N and 258N. The values of the coefficient of friction taken at different temperatures, loads and frequencies and for each of the compositions A, C and D are indicated in Table IV.

TABLE IV A C D Average coefficient of friction 0.12 0.09 0.10 (51° C., 52N, 20 Hz) Average coefficient of friction 0.14 0.11 0.11 (103° C., 115N, 10 Hz) Average coefficient of friction 0.13 0.12 0.13 (100° C., 255N, 10 Hz) Average coefficient of friction 0.12 0.10 0.10 (99° C., 257N, 40 Hz) Average coefficient of friction 0.12 0.10 0.11 (115° C., 258N, 40 Hz) Average coefficient of friction 0.14 0.10 0.12 (156° C., 255N, 5 Hz) Average coefficient of friction 0.14 0.10 0.13 (153° C., 255N, 10 Hz) Average coefficient of friction 0.14 0.10 0.12 (151° C., 255N, 20 Hz) Average coefficient of friction 0.13 0.11 0.11 (149° C., 255N, 40 Hz) Average coefficient of friction 0.12 0.11 0.11 (206° C., 113N, 40 Hz) Average coefficient of friction 0.12 0.11 0.11 (205° C., 115N, 40 Hz)

The results show that an amine compound according to the invention has anti-friction properties. The results also show that a lubricant composition according to the invention (composition C) makes it possible to obtain coefficients of friction equivalent to or even less than those of a lubricant composition comprising a usual friction modifier (composition D). Thus, on the basis of the above results, it can reasonably be envisaged that a lubricant composition according to the invention could make it possible to obtain fuel consumption gains at least equivalent to, or even greater than those obtained with a lubricant composition comprising a usual friction modifier, in particular for low-temperature use of a vehicle. 

1. A lubricant composition comprising at least one base oil and at least one amine compound of formula (I)

in which: M represents a hydronium, sodium, potassium, lithium or ammonium cation; R₁ represents a hydrogen atom or a linear or branched alkyl group, comprising from 1 to 30 carbon atoms; R₂ represents a linear or branched alkyl group, comprising from 2 to 20 carbon atoms; R₃ represents a linear or branched alkyl group, comprising from 2 to 20 carbon atoms; and n represents 2, 3, 4, 5 or
 6. 2. The lubricant composition according to claim 1 in which: M represents a sodium cation; R₁ represents a linear or branched alkyl group, comprising from 5 to 20 carbon atoms; R₂ represents a linear or branched alkyl group, comprising from 2 to 5 carbon atoms; R₃ represents a linear or branched alkyl group, comprising from 2 to 5 carbon atoms; and n represents 2, 3 or
 4. 3. The lubricant composition according to claim 1 in which R₁ represents a linear alkyl group comprising from 5 to 20 carbon atoms.
 4. The lubricant composition according to claim 1 comprising an amine compound of formula (Ia);


5. The lubricant composition according to claim 1 in which the content by weight of amine compound of formula (I) or (Ia) ranges from 0.01 to 3% with respect to the total weight of the composition.
 6. The lubricant composition according to any claim 1 comprising at least one additive chosen from detergents, anti-wear additives, extreme-pressure additives, additional antioxidants, polymers improving the viscosity index, pour point improvers, anti-foaming agents, thickeners and mixtures thereof. 7-10. (canceled)
 11. A method for reducing fuel consumption of a vehicle comprising at least one step of bringing a mechanical part of the vehicle engine into contact with a lubricant composition comprising at least one base oil and at least one amine compound of formula (I)

in which: M represents a hydronium, sodium, potassium, lithium or ammonium cation; R₁ represents a hydrogen atom or a linear or branched alkyl group, comprising from 1 to 30 carbon atoms; R₂ represents a linear or branched alkyl group, comprising from 2 to 20 carbon atoms; R₃ represents a linear or branched alkyl group, comprising from 2 to 20 carbon atoms; and n represents 2, 3, 4, 5 or 6; wherein the lubricant composition reduces the fuel consumption of the vehicle.
 12. (canceled)
 13. A method for modifying the friction properties of a lubricant composition, comprising adding to the lubricant composition an amine compound of formula (I)

in which: M represents a hydronium, sodium, potassium, lithium or ammonium cation; R₁ represents a hydrogen atom or a linear or branched alkyl group, comprising from 1 to 30 carbon atoms; R₂ represents a linear or branched alkyl group, comprising from 2 to 20 carbon atoms; R₃ a linear or branched alkyl group, comprising from 2 to 20 carbon atoms; and n represents 2, 3, 4, 5 or
 6. 14. A method for reducing the oxidation of a lubricant composition, comprising adding to the lubricant composition—an amine compound of formula (I) as defined in claim
 1. 15. The lubricant composition according to claim 2 in which R₁ represents a linear or branched alkyl group comprising from 9 to 15 carbon atoms.
 16. The lubricant composition according to claim 3 in which R₁ represents a linear alkyl group comprising from 9 to 15 carbon atoms.
 17. The lubricant composition according to claim 5, in which the content by weight of amine compound of formula (I) or (Ia) ranges from 0.5 to 2% with respect to the total weight of the composition. 